Electric power converter apparatus for an a.c. electric rolling stock

Abstract

A power converter apparatus for an a.c. electric rolling stock comprising two transformers, each including a primary winding and a plurality of secondary windings generating the same output voltages but having different internal reactances; a pair of phase-controlled bridge rectifier circuits, each being connected to one secondary winding of each transformer; and diode bridge rectifier circuits connected to the other secondary windings, wherein the windings connected to the pair of phase-controlled bridge rectifier circuits have different internal reactances, and the phase-controlled bridge rectifier circuits are simultaneously controlled, and when the maximum output voltages from the phase-controlled bridge rectifier circuits are reached, the output voltages from the diode bridge rectifier circuits (non-phase-controlled) are increased to their maximum values, then the output voltages from the phase-controlled bridge rectifier circuits are decreased to their minimum values.

What we claim is: 
     
       1. A power converter apparatus for an a.c. electric rolling stock comprising a first transformer including a primary winding and a plurality of secondary windings, said secondary windings having different internal reactances,   a single-phase a.c. power source connected to said primary winding of said first transformer,   first rectifier means including the same number of bridge rectifier circuits as said secondary windings, said bridge rectifier circuits having a.c. terminals connected to their associated secondary windings of said first transformer and d.c. terminals connected together in series between d.c. output terminals of said first rectifier means, one of said bridge rectifier circuits being a first phase-controlled bridge rectifier circuit including at least two thyristors, and the others of said bridge rectifier circuits being non-phase-controlled bridge rectifier circuits,   first load means connected between the d.c. output terminals of said first rectifier means,   first phase control means having a plurality of output terminals connected to the gate terminals of their associated thyristors of said first phase-controlled bridge rectifier circuit, said first phase control means including means for generating a first switch command and simultaneously returning phase control angles of the thyristors of said first phase-controlled bridge rectifier circuit to maximum phases when the phase control angles of said thyristors reach minimum phases,   first switching means responsive to the first switch command for allowing one of said non-phase-controlled bridge rectifier circuits of said first rectifier means to produce its maximum d.c. output voltage,   a second transformer including a primary winding connected together with the primary winding of said first transformer to said single-phase a.c. power source, and the same number of secondary windings as those of said first transformer, said secondary windings of said second transformer having the same internal reactances and output voltages as those of said first transformer,   second rectifier means including the same number of bridge rectifier circuits as said secondary windings of said second transformer, said bridge rectifier circuits having a.c. terminals connected to their associated secondary windings of said second transformer and d.c. terminals connected together in series between d.c. output terminals of said second rectifier means, one of said bridge rectifier circuits being a second phase-controlled bridge rectifier circuit including at least two thyristors, the secondary winding connected to said second phase-controlled bridge rectifier circuit being different in internal reactance from said secondary winding connected to said first phase-controlled bridge rectifier circuit, and the others of said bridge rectifier circuits being non-phase-controlled bridge rectifier circuits,   second load means connected between the d.c. output terminals of said second rectifier means,   second phase control means having a plurality of output terminals connected to the gate terminals of their associated thyristors of said second phase-controlled bridge rectifier circuit, said second phase control means including means for generating a second switch command and simultaneously returning phase control angles of the thyristors of said second phase-controlled bridge rectifier circuit to maximum phases when the phase control angles of said thyristors reach minimum phases, and   second switching means responsive to the second switch command for allowing one of said non-phase-controlled bridge rectifier circuits of said second rectifier means to produce its maximum d.c. output voltage.   
     
     
       2. A power converter apparatus for an a.c. electric rolling stock comprising a first transformer including a magnetic core, a primary winding and a plurality of secondary windings, said secondary windings being disposed in different locations on said magnetic core and thereby having different reactance values,   a single-phase a.c. power source connected to said primary winding of said first transformer,   first rectifier means including the same number of bridge rectifier circuits as said secondary windings, said bridge rectifier circuits having a.c. terminals connected to their associated secondary windings of said first transformer and d.c. terminals connected together in series between d.c. output terminals of said first rectifier means, one of said bridge rectifier circuits being a first phase-controlled bridge rectifier circuit including at least two thyristors, and the others of said bridge rectifier circuits being non-phase-controlled bridge rectifier circuits,   first load means connected between the d.c. output terminals of said first rectifier means,   a first current detector for detecting current flowing through said first load means,   first current control means for comparing an output from said first current detector with a control signal,   first phase control means responsive to an output from said first current control means for controlling phase control angles of the thyristors of said first phase-controlled bridge rectifier circuit, said first phase control means including means for generating a first switch command and simultaneously returning phase control angles of the thyristors of said first phase-controlled bridge rectifier circuit to maximum phases when the phase control angles of said thyristors reach minimum phases,   first switching means responsive to the first switch command for allowing one of said non-phase-controlled bridge rectifier circuits of said first rectifier means to produce its maximum d.c. output voltage,   a second transformer including a magnetic core, a primary winding connected together with the primary winding of said first transformer to said single-phase a.c. power source, and a plurality of secondary windings, said second transformer being identical in core and winding structures and dimensions with said first transformer whereby each secondary winding of said second transformer has the same internal reactance as its corresponding secondary winding of said first transformer,   second rectifier means including the same number of bridge rectifier circuits as said secondary windings, said bridge rectifier circuits having a.c. terminals connected to their associated secondary windings of second transformer and d.c. terminals connected together in series between d.c. output terminals of said second rectifier means, one of said bridge rectifier circuits being a second phase-controlled bridge rectifier circuit including at least two thyristors, and the others of said bridge rectifier circuits being non-phase-controlled bridge rectifier circuits, wherein the location of the secondary winding on its associated core connected to said second phase-controlled bridge rectifier circuit is not corresponding to the location of the secondary winding on its associated core connected to said first phase-controlled bridge rectifier circuit,   second load means connected between the d.c. output terminals of said second rectifier means,   a second current detector for detecting current flowing through said second load means,   second current control means for comparing an output from said second current detector with a control signal,   second phase control means responsive to an output from said second current control means for controlling phase control angles of the thyristors of said second phase-controlled bridge rectifier circuit, said second phase control means including means for generating a second switch command and simultaneously returning phase control angles of the thyristors of said second phase-controlled bridge rectifier circuit to maximum phases when the phase control angles of said thyristors reach minimum phases, and   second switching means responsive to the second switch command for allowing one of said non-phase-controlled bridge rectifier circuits of said second rectifier means to produce its maximum d.c. output voltage.   
     
     
       3. A power converter apparatus for an a.c. electric rolling stock comprising a first transformer including a primary winding and a plurality of secondary windings having different internal reactance values,   a single-phase a.c. power source connected to said primary winding of said first transformer,   first rectifier means including the same number of bridge rectifier circuits as said secondary windings, said bridge rectifier circuits having a.c. terminals connected to their associated secondary windings of said first transformer and d.c. terminals connected together in series between d.c. output terminals of said first rectifier means, each bridge rectifier circuit being a first phase-controlled bridge rectifier circuit including at least two thyristors,   first load means connected between the d.c. output terminals of said first rectifier means,   first phase control means having a plurality of output terminals connected to the gate terminals of their associated thyristors of said first phase-controlled bridge rectifier circuits,   a second transformer including a primary winding connected together with the primary winding of said first transformer to said single-phase a.c. power source, and the same number of secondary windings as those of said first transformer, each secondary winding of said second transformer having the same internal reactance and output voltage as its corresponding winding of said first transformer,   second rectifier means including the same number of bridge rectifier circuits as said secondary windings of said first transformer, said bridge rectifier circuits having a.c. terminals connected to their associated secondary windings of said second transformer and d.c. terminals connected together in series between d.c. output terminals of said second rectifier means, each bridge rectifier circuit being a second phase-controlled bridge rectifier circuit including at least two thyristors,   second load means connected between the d.c. output terminals of said second rectifier means, and   second phase control means having a plurality of output terminals connected to the gate terminals of their associated thyristors of said second phase-controlled bridge rectifier circuits, wherein the thyristors of a pair of phase-controlled bridge rectifier circuits each consisting of one selected from the respective first and second phase-controlled bridge rectifier circuits of said first and second rectifier means are simultaneously phase-controlled by said first and second phase control means to shift from maximum phases toward minimum phases, and when phase control angles of the thyristors of said pair of first and second phase-controlled bridge rectifier circuits reach minimum phases, the thyristors of another pair of first and second phase-controlled bridge rectifier circuits are simultaneously controlled in the same manner, and wherein each pair of first and second phase-controlled bridge rectifier circuits to be simultaneously controlled are selected from the two transformers to be those connected to windings having different internal reactances in their associated transformers.